os supraoccipitale

(plural ossa supraoccipitalia))

supraocciptal (a median, mixed-origin bone at the upper rear end of the cranium, often bearing a crest, and forming the upper edge of the foramen magnum. In most bony fishes its origins are from the ossification of the otic roof (tectum synoticum) and the connective median septum separating the anterior trunk muscles. Absent in Chondrostei and Holostei)